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  <script>
    var twoSum = function (nums, target) {
      let obj = {}
      for (let i = 0; i < nums.length; i++) {
        let one = nums[i]
        let other = target - one
        if (obj[one]) {
          return [obj[one].i, i]
        }
        obj[other] = { i }
      }
    };

    console.log(twoSum([1, 2, 3], 4));
  </script>
</body>

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